1. Field of the Invention
This invention relates to an industrial mulcher apparatus for use in mulching vegetation such as brush, trees, etc., or stump grinding. In particular, the invention relates. to improvements to a mulcher unit including a plurality of cutter assemblies that serially engage and mulch the intended vegetation in rapid fashion.
2. Description of the Related Art
FIGS. 1-5 illustrate a related art mulcher apparatus 10. The mulcher apparatus 10 includes a tractor 12 supported on a set of wheels 14. A tractor driver can sit within a protected cage 16 positioned on a frame of the mulcher apparatus 10. A hydraulic unit 18 connected to the tractor 12 provides structure by which a mulcher unit 20 is positioned, e.g., laterally shifted, raised and/or lowered. The tractor 12 is commercially available from Barco, a manufacturer of tractors. Also, many details of the mulcher apparatus 10 shown in FIG. 1 are described in U.S. Pat. Nos. 5,813,792 and 6,484,811, herein incorporated by reference in their entirety.
The tractor 12 is provided with one or more power sources, e.g., motors, sufficient to drive the tractor at a desired speed and to rotate the mulcher unit 20 in the direction of arrow A. The mulcher unit 20 can rotate at a speed of about 1,700 rpm, for example.
As shown in FIG. 2, the mulcher unit 20 includes a power driven rotatable shaft 22 on which a plurality of axially spaced support disks 24 are mounted. Each disk 24 includes a through hole 26 through which a support rod 28 is guided and secured, e.g., via welding. The mulcher unit 20 includes a plurality of tooth assemblies 30 each supported on the support rods 28. Each tooth assembly 30 includes a base portion 32 and a head portion 34. The head portion 34 includes a cutter element 36 described below.
As shown in FIG. 3, each base portion 32 includes one or more through holes 38 through which the support rods 28 are guided in order to support each tooth assembly 30 in a non-rotatable fashion. FIG. 3 also shows that the cutter element 36 includes a primary cutter element 40. A deflecting element or secondary cutter element 42 is provided on a central portion 43 of the tooth assembly 30 which is intermediate the base portion 32 and the head portion 34. The primary cutter element 40 may include a tip portion 44 made of a carbide material which is provided, e.g., welded or glued, to a base portion 46 of the primary cutter element 40.
Referring back to FIG. 2, the cutter element 36 is connected to the head portion 34 of the tooth assembly 30 as follows. The base portion 46 of the cutter element 36 is provided with a shroud 48 which is integrally formed with and extends away from a rear side 31a of the cutter element 36. The shroud 48 is generally oval or hour-glass shaped (see FIG. 7 and description below) and includes a pair of pre-threaded bores 33 for receiving a pair of bolts 50. The head portion 34 of the tooth assembly is provided with a countersunk aperture matching the shape of the shroud 48 so that, upon assembly, the cutter element 36 and the head portion 34 fit together like a puzzle. In FIG. 2, the bolts 50 and the shroud 48 of one of the tooth assemblies 30 are shown in phantom to facilitate understanding of the connection between the cutter element 36 and the head portion 34.
FIGS. 4 and 5 show alternative versions of the cutter element. FIG. 4 includes a cutter element 36′ having a pair of tip portions 44′ provided on a base portion 46′. FIG. 5 illustrates a cutter element 36″ including first and second rows of tip portions 44′ that are provided to a base portion 46″.
There are several disadvantages associated with the mulcher apparatus shown in related art FIGS. 1-5. In particular, with respect to the connection between the cutter element 36 and the head portion 34, the provision of a raised shroud 48 with pre-threaded bores requires difficult machining operations and is therefore relatively expensive to manufacture. In addition, the mounting assembly for mounting the tooth assembly 30 to the rotatable shaft 22 is difficult and cumbersome, in part, because it requires a plurality of support disks 24 having bores 26 for receiving rods 28. Also, the central portion 43 requires a secondary cutter or deflecting element since it may inadvertently contact the intended target. Finally, the positioning of each tooth element is such that a significant number of the cutter elements 36 may contact the intended target at the same time, thereby slowing rotation of the shaft 22 with a commensurate decrease in power.
Accordingly, a need has developed in the art to provide a mulcher apparatus which addresses the above-noted deficiencies.